He needs at least one central midfielder and, with Nemanja Vidic leaving at the end of the season, a new centre-half.

The United manager has also been keen to add a left-back and that need may intensify if Patrice Evra doesn't agree an extension to his contract.

Here is a list of 10 targets United and Moyes might look at this summer, from least to most likely.

As always, feel free to add your own in the comments section below.

10. Toni Kroos

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It's easy to see why David Moyes might be interested in Toni Kroos, per the Telegraph's Jason Burt, especially after his performance against Arsenal in the Champions League last week.

But, in the same breath, it's easy to see why Bayern Munich and Pep Guardiola will want to keep him.

Moyes is expected to sign at least one central midfielder in the summer and players of Kroos' quality will certainly be on his list.

But the difficulty will be persuading the 24-year-old to leave a club that has visions of dominating European football for the next decade.

9. Mats Hummels

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David Moyes probably won't admit it but losing Nemanja Vidic at the end of the season is a blow.

At 32, the Serbian defender still had a role to play at Old Trafford. And now Moyes is faced with a decision over whether to replace him or find a new centre-half pairing in Phil Jones, Jonny Evans and Chris Smalling.

Borussia Dortmund defender Mats Hummels is one of the best centre-halves in the world, particularly comfortable on the ball but whether he would pick United is open to debate.

8. Sami Khedira

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Real Madrid midfielder Sami Khedira has missed almost the entire season with a knee injury he suffered in November.

In his absence, Xabi Alonso has signed a new contract, Luka Modric is playing well and Asier Illarramendi is finding his feet after his summer move from Real Sociedad.

David Moyes might hope Khedira fancies a new challenge after the World Cup, or that Real Madrid feel they can cope without him.

A fully fit Khedira, still only 26, is exactly the type of midfielder United have been missing.

7. Claudio Marchisio

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Juventus midfielder Claudio Marchisio is another midfielder who would fit perfectly into United's team but another who will need to be convinced to leave his club.

Marchisio faces competition from Paul Pogba, Andrea Pirlo and Arturo Vidal in Turin, but he's a Juventus fan and has been at the club since he was a youngster.

At 28, he hasn't got as much time on his side as Toni Kroos or Sami Khedira but he would still improve United's midfield.

6. Ross Barkley

But it's under new manager Roberto Martinez that the 20-year-old has flourished, his performances in his first season as an Everton regular pushing him to the brink of England's World Cup squad.

Young and English, Barkley fits the profile for preferred United signings—much like Phil Jones, Chris Smalling and Nick Powell.

But Everton and Martinez are desperate to keep him and it may be a little early in his development for a big-money move.

5. Marco Reus

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Borussia Dortmund forward Marco Reus would add pace to United's forward line but they will face competition for his signature if he decides to leave the Westfalenstadion.

Ashley Young, Antonio Valencia and Nani have struggled for form and fitness this season and Reus would certainly be an upgrade.

But his performances in last season's Champions League alerted the world to what everyone in Germany already knew, and it's questionable whether Reus would choose United—who might not be in the Champions League—as his next destination.

4. Eliaquim Mangala

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United have sent scouts to watch Porto's French defender Eliaquim Mangala a number of times since the turn of the year, per Jamie Jackson of The Guardian.

At 23-years-old he would be considered as a long-term replacement for Nemanja Vidic—and Rio Ferdinand, if he isn't offered a new deal at Old Trafford.

There will be plenty of other interested parties if he is allowed to leave Porto in the summer. And he won't come cheap with only bids of more than £40milllion likely to be considered.

Porto have developed a reputation for selling their stars for big money and replacing them with talented youngsters unearthed by their wonderful scouting network.

3. Ilkay Gundogan

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The longer Ilkay Gundogan goes without signing a new contract at Borussia Dortmund, the more encouraged United and David Moyes will become.

The issue isn't whether Gundogan would fit into United's team but whether United fit into the German midfielder's career path.

Still only 23, he's highly-rated throughout Europe and Moyes might end up having to sell a club with no Champions League football should Gundogan decide to entertain offers in the summer.

2. Fernando

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It was a surprise to some that United didn't make more of an effort to sign Porto's Brazilian midfielder Fernando in the January transfer window.

Out of contract in the summer, he will almost certainly leave Portugal at the end of the season.

Without a transfer fee to pay, the 26-year-old would represent a cheaper option than Toni Kroos, Sami Khedira and Ilkay Gundogan but David Moyes might set his sights a little higher.

But should Moyes decide he needs two midfielders, signing Fernando on a free transfer would be ideal.

1. Luke Shaw

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Patrice Evra gave a timely reminder of his quality against Crystal Palace on Saturday.

But, out of contract in the summer, his future at Old Trafford is far from secure.

Back-up Alex Buttner isn't good enough to be considered a regular starter and David Moyes has been keen to add a new left-back to his squad since taking over from Sir Alex Ferguson.

Only 18, Southampton left-back Luke Shaw is considered one of the brightest prospects in England.

Moyes could yet convince Evra to stay for another season and it might appeal to the United manager to let him share the responsibilities at left-back with Shaw.